High School Earth Science: Human Actions and Earth’s Water - Water Pollution — Flashcards

Sources of Water Pollution    
Water pollution is any contaminant that gets into lakes, streams, or oceans. Water pollution is a worldwide problem.    
In less developed countries, the main source of water pollution is raw sewage that is dumped into water that people must use for drinking and bathing. In more developed countries, sources of water pollution include municipal, industrial, and agricultural sources.    
- Municipal sources of water pollution come from the wastewater of cities and towns. The wastewater contains many different contaminants from homes and businesses. The contaminants come from inadequately treated sewage, storm drains, septic tanks, boat sewage, and yard runoff, among other sources.    
- Industrial pollution comes from factories, power plants, and even hospitals. Some of the most hazardous industrial pollutants include radioactive substances, heavy metals, organic toxins, chemicals, oil and other petroleum products, and heated water.    
- Agricultural pollution comes mainly from runoff water. Water running over farm fields and animal pens picks up fertilizers, pesticides, and animal wastes and carries them to bodies of water such as streams, lakes, and oceans.    
  
Fertilizers deserve special mention as sources of water pollution. They are found in runoff from lawns, golf courses, and farm fields. Nutrients such as nitrates in fertilizers promote the growth of algae, so bodies of water polluted with fertilizers become clogged with algae. When the algae die, they decompose, and decomposition uses up all the dissolved oxygen in the water. Without oxygen, the water can no longer support aquatic organisms, including plants and fish. This creates dead zones, or areas of water in lakes and oceans that lack fish and most other aquatic organisms.